Seamless foldable display device

ABSTRACT

A foldable display device is designed so that a junction between at least two display panels connected to each other is not visibly seen. The display device displays an image on a plurality of display panels that are connected together. Pixels near the junction between every two adjacent display panels of the at least two display panels are smaller and have a higher brightness than the other pixels.

This application claims priority to Korean Patent Application No.10-2006-0041638, filed on May 9, 2006, and all the benefits accruingtherefrom under 35 U.S.C. §119, the contents of which in its entiretyare herein incorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a foldable display device, and moreparticularly, to a foldable display device having a junction between atleast two display panels connected to each other which is not visiblynoticeable.

2. Description of the Related Art

As mobile multimedia broadcasting services, such as, digital multimediabroadcasting, is increasingly being provided, the necessity of enlarginga display panel of a portable display device, such as, a compact mobiledevice (e.g., a mobile phone) or a portable multimedia player (“PMP”),is increasing. However, the enlargement of the display panel greatlydecreases the portability of the portable display device.

To solve this problem, a foldable display device including two displaypanels 10 a and 10 b which are pivotally coupled to each other so thatthe foldable display device may be folded while being carried has beenproposed, which is illustrated in FIG. 1. However, two pixels 12 a and12 b located at junction parts of the display panels 10 a and 10 b,respectively, are separated by about 1 mm, so that a black stripe Bappears between images displayed on the two display panels 10 a and 10b. In order to minimize a thickness of the black stripe B, the distancebetween the pixels 12 a and 12 b at junction parts of the display panels10 a and 10 b needs to be minimized. The thicknesses of barrier walls 11a and 11 b for completely shielding the pixels within the display panels10 a and 10 b from the outside hinder sufficient minimization of thedistance between the pixels 12 a and 12 b. This problem not only occursin portable foldable display devices but also in large-sized displaydevices that have large screens obtained by connecting a plurality ofsmall display panels together.

To address this problem, a technique of providing a continuous image byremoving a black stripe without reducing the distance between the pixels12 a and 12 b installed on the junction parts of the display panels 10 aand 10 b has been proposed. FIG. 2 illustrates a conventional displaydevice having two display panels between which there are no seams.Referring to FIG. 2, the display panels 20 a and 20 b are coupled toeach other by a junction part 21. To optically compensate for the seambetween the two display panels 20 a and 20 b, electrodes 25 near thejunction part 21 are made smaller than electrodes 24 in the other parts.To magnify the images on the smaller electrodes 25, a convex opticallens 23 is installed over the smaller electrodes 25. On the other hand,a flat glass or optical lens 22 is installed over the larger electrodes24. Backlight units 26 a and 26 b for illuminating the display panels 20a and 20 b, respectively, may be designed so as to provide brighterlight to the smaller electrodes 25 than to the larger electrodes 24.

However, because the conventional display device of FIG. 2 requires theextra optical lens 23, the number of components thereof increases,leading to increases in the manufacturing time and costs thereof. Also,if the curvatures of the optical lens 23 is not precisely designed, animage may be distorted due to, for example, aberration. In addition, theprecision design of the optical lens 23 increases the manufacturingcosts greatly. Moreover, it is difficult to design the backlight units26 a and 26 b for providing brighter light to a specific area, namely,to the smaller electrodes 25 than to the larger electrodes 24, and thedesign of the backlight units also increases the manufacturing costs.Furthermore, the backlight units 26 a and 26 b can hardly control thebrightness of the specific area with any precision.

BRIEF SUMMARY OF THE INVENTION

The present invention provides a foldable display device which makes ajunction between at least two display panels connected to each otherinvisible, using a method that does not require additional componentsand is thus simple and cost-effective compared to conventional methods.

According to an aspect of the present invention, a display device isprovided for displaying an image on a plurality of display panels thatare connected together, wherein pixels near a junction between every twoadjacent display panels of the display panels are smaller than the otherpixels and the smaller pixels near the junction between the every twoadjacent display panels have a higher brightness than the other pixels.

In an exemplary embodiment of the present invention, two facing pixelson both sides of the junction between the every two adjacent displaypanels may serve as independent pixels.

In this exemplary embodiment, when vertical pixel lines of the every twoadjacent display panels are divided into continuous areas havingidentical widths, a single pixel may be located in each of the areas.

In this exemplary embodiment, pixels in at least two pixel columns maygradually increase in a direction going from the junction of the everytwo adjacent display panels to each of the center portions of the everytwo adjacent display panels.

In this exemplary embodiment, the intensity of light emitted from one ofthe pixels near the junction of the every two adjacent display panels isequal to the intensity of light emitted from one of the other pixels.

In another exemplary embodiment of the present invention, two facingpixels on both sides of the junction between the every two adjacentdisplay panels may serve as a single pixel.

In this exemplary embodiment, when vertical pixel lines of the twoadjacent display panels are divided into continuous areas havingidentical widths, the two pixels on both sides of the junction arelocated together in one area, and the other pixels are arranged in sucha manner that one pixel is located in one area.

In this exemplary embodiment, the sum of the intensities of lightsemitted from the two pixels on both sides of the junction is equal tothe intensity of light emitted from one of the other pixels.

In the present invention, the display panels are emissive displaypanels.

The display panels may be one of an organic electroluminescent lightemitting device (“OLED”), a field emission display (“FED”), a plasmadisplay panel (“PDP”), and an inorganic electroluminsecence (“EL”)device.

The junction between the every two neighboring display panels mayinclude a hinge to allow the every two neighboring display panels to befolded one over the other.

The distance between the pixels on both sides of the junction betweenthe every two adjacent display panels may be in the range of about 0.1mm to about 1 mm.

An array of pixels that display a red color (R), a green color (G) and ablue color (B) may be repeated in a direction substantially parallel toa lengthwise direction of the junction.

According to another aspect of the present invention, a method fordisplaying an image on a plurality of display panels connected togetheris provided. The method includes: disposing pixels near a junctionbetween every two adjacent display panels of the plurality of displaypanels being smaller than the other pixels; and illuminating the smallerpixels near the junction between the every two adjacent display panelsto have a higher brightness than the other pixels.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features and advantages of the presentinvention will become more apparent by describing in more detailexemplary embodiments thereof with reference to the attached drawings inwhich:

FIG. 1 is a plan view and a partial cross-sectional view illustrating aconventional foldable display device;

FIG. 2 is a cross-sectional view illustrating another conventionalfoldable display device;

FIG. 3 is a block diagram illustrating a configuration of pixelsemployed in a seamless foldable display device according to an exemplaryembodiment of the present invention so as to make a seam invisible;

FIG. 4A is a block diagram illustrating an edge structure of a displaypanel that uses a pixel having a general length;

FIG. 4B is a block diagram illustrating an edge structure of a displaypanel that uses a pixel having a short length;

FIGS. 5A and 5B are block diagrams illustrating different configurationsof pixels in the foldable display device of FIG. 3; and

FIG. 6 is a block diagram illustrating a configuration of pixels that isemployed in a seamless foldable display device according to anotherexemplary embodiment of the present invention so as to make a seaminvisible.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 3 is a block diagram illustrating a configuration of pixels of aseamless foldable display device according to an exemplary embodiment ofthe present invention for displaying a single image on a plurality ofdisplay panels that are connected together.

As illustrated in FIG. 3, the seamless foldable display device includestwo display panels 30 a and 30 b which are connected together. Althoughonly the two display panels 30 a and 30 b are illustrated in FIG. 3,more than two display panels may be included in the seamless foldabledisplay device. The principle according to the present invention isequally applied to this case. In the present exemplary embodiment,pixels 34 a and 34 b adjacent to a junction 31 between the two displaypanels 30 a and 30 b among the pixels arranged on the two display panels30 a and 30 b are formed to be smaller than the other pixels 33 a and 33b. The smaller size of the pixels 34 a and 34 b are offset bycontrolling the pixels 34 a and 34 b to have a higher brightness thanthe pixels 33 a and 33 b. If an array of a red (R) pixel, a green (G)pixel and a blue (B) pixel are repeated in the horizontal direction,specific color pixels may be small. To prevent this problem, an array ofR, G and B pixels is preferably repeated in a lengthwise direction ofthe junction 31, that is, in the vertical direction as illustrated inFIG. 3.

The junction 31 may be simply formed of an adhesive material that joinsthe two display panels 30 a and 30 b together. However, the twoneighboring display panels 30 a and 30 b may be designed to be foldedone over the other by, for example, a hinge. In this case, a displaydevice according to the present invention may be used as a portablefoldable display device that can be transported with the two displaypanels being folded against one another to minimize the size of thedisplay device, thus facilitating portability.

In the present exemplary embodiment, the display panels 30 a and 30 bare emissive display panels that do not use backlight units. Examples ofthe display panels 30 a and 30 b include an organic electroluminescentlight emitting device (“OLED”), a field emission display (“FED”), aplasma display panel (“PDP”), an inorganic electroluminsecence (“EL”)device, etc. In the present invention, since emissive display panels areused as the display panels 30 a and 30 b, the brightnesses of onlyspecific pixels can be precisely increased to desired levels simply byincreasing the duration or intensity of an applied voltage to only thosespecific pixels.

As illustrated in FIG. 3, the distance between the pixels 34 a and 34 badjacent to the junction 31 between the two display panels 30 a and 30 bcan be reduced by decreasing the sizes of the pixels 34 a and 34 b. Asillustrated in FIG. 4A, in an edge of a display panel that uses a pixel33 having a general or standard length, the junction 31 of FIG. 3 shouldbe formed on the outer side of a barrier wall 36 for protecting thepixel 33. Here, the distance between the pixel 33 and the barrier rib36, the thickness of the barrier wall 36, and the structure andthickness of the junction 31 determine the distance between the pixels34 a and 34 b on both sides of the junction 31. As illustrated in FIG.4B, when the pixel on the edge of the display panel is shortened into apixel 34, the distance between the pixel 34 and the barrier wall 36 canbe shortened by the reduced length of the pixel. In addition, in thepresent invention, the overall thickness of the barrier wall 36 and thejunction 31 can be reduced by integrally forming the barrier wall 36 andthe junction 31.

In this case, the distance between the pixels 34 a and 34 b near thejunction 31 between the two display panels 30 a and 30 b may be in therange of about 0.1 mm to about 1 mm. In general, when the distancebetween two points is 0.1 mm, the two points appear as a single point ata distance of 40 cm or more. Hence, when the distance between the pixels34 a and 34 b is in the range of about 0.1 mm to about 1 mm, a blackstripe between images displayed on the two display panels 30 a and 30 bmay be hardly seen.

FIGS. 5A and 5B illustrate configurations of pixels of a display deviceaccording to the present invention that help allow a black stripebetween the two display panels 30 a and 30 b to be more invisible andtwo images displayed on the two display panels 30 a and 30 b to besmoothly connected to each other.

In the case of FIG. 5A, the two pixels 34 a and 34 b facing each otheron both sides of the junction 31 of the two display panels 30 a and 30 bserve as a single pixel. In other words, the two pixels 34 a and 34 bare controlled to display the same image data at all times. Asillustrated in FIG. 5A, when vertical pixel lines of the two adjacentdisplay panels 30 a and 30 b are divided into continuous areas A havingidentical widths, the two pixels 34 a and 34 b on both sides of thejunction 31 are located together in one area, and the other pixels 33 aand 33 b are arranged in such a manner that one pixel is located in onearea A. In this case, the sum of the intensities of lights emitted fromthe two pixels 34 a and 34 b together is controlled to be equal to theintensity of light emitted from each of the pixels 33 a and 33 b. Forexample, if the sum of the sizes of the pixels 34 a and 34 b is ⅔ of thesize of a pixel 33 a or 33 b other than the pixels 34 a and 34 b, thesum of the intensities of light emitted from the two pixels 34 a and 34b is controlled to be 3/2 of the brightness of the pixel 33 a or 33 bother than the pixels 34 a and 34 b. By doing this, the pixels 33 a, 33b and 34 a/34 b of the display panels 30 a and 30 b look to beconsecutively arranged at regular intervals. Accordingly, a black stripegenerated due to the junction 31 can be minimized, and images displayedon both sides can be smoothly connected to each other.

In the case of FIG. 5B, the two pixels 34 a and 34 b facing each otheron both sides of the junction 31 of the two display panels 30 a and 30 bserve as independent pixels in respective areas A. In other words, thetwo pixels 34 a and 34 b are controlled to display different image dataindependently. As illustrated in FIG. 5B, when vertical pixel lines ofthe two adjacent display panels 30 a and 30 b are divided intocontinuous areas A having identical widths, a single pixel is located ineach of the areas A. Accordingly, the two pixels 34 a and 34 b smallerthan the other pixels 33 a and 33 b are located in different areas Alike the other pixels 33 a and 33 b arranged in such a manner that onepixel is located in one area A. In this case, the intensity of lightemitted from each of the two pixels 34 a and 34 b is controlled to beequal to the intensity of light emitted from each of the pixels 33 a and33 b. For example, if the size of one of the pixels 34 a and 34 b is ½of the size of a pixel other than the pixels 34 a and 34 b, theintensity of light emitted from one of the two pixels 34 a and 34 b iscontrolled to be twice the brightness of the pixel 33 a or 33 b otherthan the pixels 34 a and 34 b. By doing this, the pixels of the displaypanels 30 a and 30 b look to be consecutively arranged at regularintervals. Accordingly, a black stripe generated due to the junction 31can be minimized, and images displayed on both sides can be smoothlyconnected to each other.

In the exemplary embodiments of FIGS. 5A and 5B, only the pixels 34 aand 34 b on both sides of the junction 31 among the pixels arranged onthe two display panels 30 a and 30 b are made smaller. However, as inthe exemplary embodiment of FIG. 6, pixels 34 a′, 34 a″, 34 a′″, 34 b′,34 b″ and 34 b′″ in a plurality of columns may gradually increase in adirection away from the junction 31 between the display panels 30 a and30 b to the center portions of the display panels 30 a and 30 b. Even inthis case, as illustrated in FIG. 5B, all of the pixels of the displaypanels 30 a and 30 b may serve as independent pixels regardless of thesizes of the pixels. In addition, when vertical pixel lines of the twoadjacent display panels 30 a and 30 b are divided into continuous areasA having identical widths, a single pixel is located in each of theareas A regardless of the different sizes of the pixels. In this case,the intensities of lights emitted from all of the pixels are controlledto be identical with one another regardless of the sizes of the pixels.

As described above, a display device for displaying an image on aplurality of display panels connected together according to the presentinvention is capable of effectively preventing or substantially reducinga black stripe associated with a junction between two adjacent displaypanels, thus making the junction invisible using a simple method. Inother words, in contrast with conventional display devices, the displaydevice according to the present invention requires no special opticallenses. In addition, the display device according to the presentinvention uses self-luminant display panels, so that the brightness ofspecific pixels can be easily controlled to desired levels. Therefore, areduction of the sizes of pixels can be easily compensated for, and acomplicated change of design of a backlight unit is not needed.Furthermore, the size of the junction between the two display panels canbe reduced, and accordingly the distance between two facing pixels onboth sides of the junction can be reduced. Therefore, discontinuity ofan image due to the junction hardly occurs compared with conventionaldisplay devices.

While the present invention has been particularly shown and describedwith reference to exemplary embodiments thereof, it will be understoodby those of ordinary skill in the art that various changes in form anddetails may be made therein without departing from the spirit and scopeof the present invention as defined by the following claims.

1. A display device for displaying an image on a plurality of displaypanels connected together, wherein pixels near a junction between everytwo adjacent display panels of the plurality of display panels aresmaller than the other pixels and the smaller pixels near the junctionbetween the every two adjacent display panels have a higher brightnessthan the other pixels, wherein pixels in at least two adjacent pixelcolumns are smaller than remaining pixels and pixels in the at least twopixel columns gradually increase in size in a direction going from thejunction of the every two adjacent display panels to each of therespective center portions of the every two adjacent display panels. 2.The display device of claim 1, wherein a width of a pixel column isuniform throughout the plurality of display panels, and whereindistances between the smaller pixels and the other pixels adjacentthereto are adjusted such that a distance between centers of the smallerpixels and a center of their respective pixel column increases withproximity to the junction.
 3. The display device of claim 1, wherein anintensity of light emitted from one of the pixels near the junction ofthe every two adjacent display panels is equal to an intensity of lightemitted from one of the other pixels.
 4. The display device of claim 1,wherein two facing pixels on both sides of the junction between theevery two adjacent display panels serve as a single pixel.
 5. Thedisplay device of claim 4, wherein the sum of intensities of lightemitted from the two pixels on both sides of the junction is equal to anintensity of light emitted from one of the other pixels.
 6. The displaydevice of claim 1, wherein the display panels are emissive displaypanels.
 7. The display device of claim 6, wherein the display panels areone of an organic electroluminescent light emitting device (OLED), afield emission display (FED), a plasma display panel (PDP) and aninorganic electroluminsecence (EL) device.
 8. The display device ofclaim 1, wherein an array of pixels that display a red color (R), agreen color (G), and a blue color (B) is repeated in a directionsubstantially parallel to a lengthwise direction of the junction.
 9. Thedisplay device of claim 1, wherein the pixels near the junction betweenevery two adjacent display panels are arranged such that a distancebetween the pixels near the junction and the other pixels is larger thana distance between the other pixels.
 10. The display device of claim 1,wherein a width between opposite ends of two pixels near the junctionbetween every two adjacent display panels is equal to a width of theother pixels.
 11. The display device of claim 1, wherein a distancebetween the pixels on both sides of the junction between the every twoadjacent display panels is in a range of about 0.1 mm to about 1 mm.